Alexei Navalny, Russia's top opposition leader and President Vladimir Putin's fiercest foe, died in prison on Friday, a statement from the Federal Penitentiary Service said.

Navalny, who was serving a 19-year sentence on charges of extremism, felt unwell after a walk and collapsed, it said. The politician's team had no immediate confirmation of his death.

World leaders and Russian opposition activists wasted no time Friday in blaming the reported death of imprisoned opposition leader Alexei Navalny on President Vladimir Putin and his government.

"It is obvious that he was killed by Putin," said Ukrainian President Volodymyr Zelenskyy, who was visiting Berlin as he sought aid for his country as it fights off an invasion by Russia.

What would it mean if Russia used nuclear warheads to destroy U.S. satellites? Your home's electrical and water systems could fail. Aviation, rail and car traffic could come to a halt. Your cellphone could stop working.

These are among the reasons why there was alarm this week over reports that Russia may be pursuing nuclear weapons in space.

In a square near the center of Algiers, currency traders carry wads of euros, pounds and dollars, hoping to exchange them to those worried about the plummeting value of the Algerian dinar.

This black market for foreign currencies is among the signs of the economic woes plaguing Algeria. The state, reluctant to allow the exchange rate to adjust fully, has proven incapable of limiting demand among the population as confidence in the dinar remains low.

Alexei Navalny, the fiercest foe of Russian President Vladimir Putin who crusaded against official corruption and staged massive anti-Kremlin protests, died in prison Friday, Russian authorities said. He was 47.

Navalny, who was serving a 19-year sentence on charges of extremism, felt unwell after a walk, according to the Federal Penitentiary Service, and lost consciousness. An ambulance arrived to try to revive him, but he died. It said the cause of death was "being established."

Egypt is building a wall and is leveling land near its border with the Gaza Strip ahead of a planned Israeli offensive targeting the border city of Rafah, satellite images analyzed Friday by The Associated Press show.

Egypt, which has not publicly acknowledged the construction, repeatedly has warned Israel not to forcibly expel the over 1 million Palestinians now displaced in Rafah across the border into its territory while it battles the militant group Hamas for a fifth month.

Five patients in intensive care died after their oxygen cut off in southern Gaza's main hospital that was stormed by Israeli troops, causing chaos for hundreds of staff and wounded inside, health officials said Friday. Troops were searching the complex where the military said it believes the remains of hostages abducted by Hamas might be located.

The raid came after troops had besieged Nasser Hospital in the southern city of Khan Younis for nearly a week, with staff, patients and others inside struggling under heavy fire and dwindling supplies, including food and water. The Israeli military said Friday it had detained dozens from the facility, including some it alleged were involved in Hamas' Oct. 7 attack on Israel.

Ukrainian President Volodymyr Zelensky arrived in Berlin on Friday on a visit aimed at rallying Western support for his embattled troops ahead of the second anniversary of the war.

Zelensky published photos on Telegram showing him arriving in Germany and said he would discuss "a new security architecture for Ukraine", adding that his country was trying to "end the war as soon as possible on fair Ukrainian terms". He will also visit Paris on Friday as he is expected to sign bilateral security agreements with Germany and France on Friday.

Israeli Prime Minister Benjamin Netanyahu said Friday that Israel will not accept what he portrayed as “international dictates” regarding a resolution of the conflict with the Palestinians.

Writing early Friday on X, Netanyahu said such a resolution can only be the result of negotiations. He also said Israel opposes a unilateral recognition of statehood, claiming it would amount to a “huge reward” for the militant group Hamas following its deadly Oct. 7 attack on Israel.

Hezbollah said Thursday it had fired dozens of rockets into northern Israel, a day after Israeli strikes killed 15 people, including one of its commanders.

"Islamic resistance fighters fired dozens of Katyusha-type rockets at Kiryat Shmona," an Israeli town near the Lebanese border, Hezbollah said in a statement.